1. Field of the Invention
The present general inventive concept relates to an image photographing apparatus, and more particularly, to a zoom switch assembly to control a zoom lens of an image photographing apparatus, an image photographing apparatus having the same, and a method of controlling a zoom lens.
2. Description of the Related Art
Usually, an image photographing apparatus such as a digital still camera or a camcorder photographs and records a desired image as a still image or a motion image and plays back the image.
Such an image photographing apparatus includes a zoom lens assembly so that an object located a long distance away from the zoom lens assembly appears to be a short distance away. The zoom lens assembly includes a zoom switch assembly to perform a zoom operation, that is, tele/wide (T/W) function, by moving the zoom lens.
The zoom switch assembly includes a knob that a user manipulates. The control unit of the image photographing apparatus determines the position of the knob of the zoom switch assembly using variation of resistance, and adjusts the zoom motor which drives the zoom lens according to the position of the knob in order to control the position of the zoom lens.
The conventional zoom switch assembly moves a brush formed integrally with the knob on a carbon plate with friction to cause the resistance of the zoom switch to be varied according to the position of the knob. The control unit of the image photographing apparatus may determine the position of the knob by measuring the resistance of the zoom switch.
However, in the conventional zoom switch assembly, since the brush made of stainless steel (SUS) causes friction with the carbon plate, there is a problem that a surface of the carbon plate is scratched.
In addition, the conventional zoom switch assembly requires a lot of components in order to assemble the carbon plate and the brush which are formed as separate modules, thereby causing difficulty in assembling.
As the conventional zoom switch assembly uses resistance on a contacting surface between the brush and the carbon plate to adjust the zoom lens, the brush must maintain the constant pressure against the carbon plate in order to accurately control the zoom switch assembly. However, the elastic member which maintains pressure between the brush and the carbon plate at a constant level may be deformed if the zoom switch assembly is used for long periods of time, and thus the pressure may be changed. The change of the pressure of the brush causes the resistance to be changed, thereby causing the difficulty in precisely controlling the zoom lens.
Accordingly, a zoom switch assembly is needed which can resolve the problem on the conventional zoom switch assembly.